Furthermore, the association between child sexual abuse and poor psychological health in adult life is now well established (Andrews et al, 2004). Research is now studying the extent to which childhood adversity is associated with persistence of symptoms or disorder, particularly in psychosis.

In this systematic review and meta-analysis published recently in Psychological Medicine (Trotta et al, 2015), the impact of childhood adversity on psychotic experiences and symptomatic outcomes from clinical states is examined.

This review looked at the relationship between childhood adversity and psychotic symptoms.

Methods

The authors conducted a systematic review of all publications in Medline, EMBASE and PsychINFO databases up to the end of November 2014 that investigated childhood adversity, psychosis, and course of psychotic experiences and symptoms.

Publications were included only if they had sufficient follow-up data to judge psychotic experience or symptomatic outcome – unfortunately for generalisability, articles in languages other than English were excluded.

From this search, 20 studies were eligible for inclusion:

9 assessing the general population

3 the ultra-high risk state

4 first-episode psychosis

4 non-first episode patients

However, only 13 were regarded as methodologically robust on the basis of a quality assessment score.

Results

In general population samples, there was some evidence of an association between persistence of psychotic experiences and childhood adversity. Only one of these papers failed to show such an association.

In ultra-high risk samples, the main outcome variable was transition to psychosis rather than persistence of subthreshold symptoms. All three studies suggested increased risk of transition in those with a history of childhood adversity, which may be specific to sexual trauma.

In patients with frank psychotic disorder the results were more mixed, with some positive associations and some negative. This may be due to the overall small numbers in these studies, or the focus on different measures of adversity or outcome making comparison difficult.

A meta-analysis was conducted on those papers that reported odds ratios (OR) between childhood adversity and persistence of psychotic symptoms:

This suggested a significantly elevated risk of symptom persistence in those with a history of childhood adversity in the general population (OR 1.76, CI 1.19 to 2.32; 5 studies)

However, there was significant heterogeneity between these papers, suggesting there may be problems combining them. While the OR in clinical groups was similar (OR 1.55), the confidence interval included 1 (CI 0.32 to 2.77) suggesting this was non-significant. There is confusion on this point though, because the authors state that this was actually significant (p=0.007).

Can we trust the tentative finding that childhood adversity is significantly linked to an elevated risk of psychotic symptom persistence?

Strengths and limitations

The authors have covered the spectrum of psychotic symptomatology, from non-clinical experiences in the general population, through ultra-high risk individuals, to those with frank psychosis.

However, there are several serious limitations:

The main one, acknowledged by the authors themselves, is that there is huge variability in definitions of childhood adversity, and in their method of assessment, making comparisons between studies in the review extremely difficult and of limited value.

The meta-analysis is also problematic. Only 9 studies could be included, but only a third of them were methodologically acceptable by the authors’ own measure. There is also some confusion about the significance of one of the results mentioned above, which reduces the value of the analysis.

Finally, when reviewing the three studies of ultra-high risk patients, the authors did not notice that two of the three are actually reporting the same population, with different follow-up intervals.

Should reviews in this field focus on specific types of childhood adversity to make the results more applicable in practice?

Conclusion

The authors appropriately note that the evidence to date is methodologically limited, but that is of sufficient value to tentatively support a role for childhood adversity in the course of psychotic phenomena.

While this has potential value for understanding the mechanisms by which psychotic phenomena persist, from an intervention perspective it is not clear that this adds very much beyond what we already know.

Stephen Wood is Professor of Adolescent Brain Development and Mental Health in the School of Psychology at the University of Birmingham. He has a particular interest in the development of severe mental illness, using a variety of techniques to predict those at greatest risk.

Childhood adversity and psychotic symptoms: seeing the Wood rather than just the Trees

We thank Mental elf and Stephen Wood for providing a clear summary of our paper and giving us the opportunity to comment on it.

We think it is important to highlight that out of 2824 published studies that were potentially relevant to our review only 20 (0.7%) were eligible, but as few as 14 (0.5%) were of a reasonable level of methodological quality. This process and its outcome is not a limitation of the study we conducted but it is instead indicative of the current state of the art in this particular research field: inconsistent terminology, utilisation of a variety of research tools (ranging from self-report questionnaires to semi-structured interviews), confusing or conflicting definitions, and heterogeneity of designs. This is also reflected in the meta-analysis we performed on a subgroup of studies. As correctly pointed out, the wide confidence intervals containing 1 for the pooled result for the clinical studies reduces the value of the analyses. However, the overall pooled estimate was suggestive of an association between childhood adversity and persistence of psychotic symptoms. Furthermore, although two of the studies on ultra-high risk patients included patients treated at the same service, the samples used were recruited during two different periods of time which did not overlap.

Finally, we stress again the high heterogeneity of studies, which urges caution in interpreting the results, and the need for more methodologically robust research. In order to begin to address this, we have recently published a paper on the impact of different childhood adversities on 1-year outcomes of first episode psychosis (Trotta et al., 2015; bit.ly/1MaXfTS).

In conclusion, our systematic review identified a rather large gap in the available literature on childhood adversity and persistence of psychotic phenomena, with our exploratory meta-analysis providing a plausible estimate of association that can be tested in subsequent studies. Further research is now needed to develop a greater understanding of which individuals with psychosis are likely to have the poorest outcomes and whether this is associated with exposure to different forms of adversity as this would assist clinicians in targeting interventions at those patients with the highest risk of a poor prognosis.